Analog cellular services in the United States were developed in the 1970s by
AT&T and were widely deployed by the late 1980s. They were implemented in
a standard format so that all telephones worked on all analog cellular networks
in the United States. However, analog cellular services became so popular that
capacity was not adequate for future growth, particularly in metropolitan areas.

As a result, digital cellular was developed to add capacity and advanced features.
Digital cellular offers features such as caller ID, call forwarding, and three-way
calling. In addition, many of the handsets have paging, long battery lives,
and short messaging services integrated via a liquid crystal display. The advent
of digital cellular and Personal Communications Service (PCS) led to price decreases
and affordable cellular for residential consumers. In 1998, for the first time,
the sale of digital handsets exceeded that of analog handsets.

Wireless Services

Service

Frequencies

Features

Comments

Analog Cellular

824MHz to 893MHz

Provides basic calling and voicemail, and low-cost phones.

Each area has two providers, the local telco and a competitor. All
telephones can be used on all analog service.

Digital Cellular

824MHz to 893MHz

Provides advanced features such as caller ID and telephones with built-in
pagers, and longer battery life.

Verizon, Sprint, and AirTouch use CDMA.

SBC, BellSouth, AT&T Wireless, and Bell Mobility use TDMA.

Nextel

800MHz to 900MHz

Has all of the same features as digital cellular.

Nextel is the only cellular provider that uses these frequencies.

Global System for Mobile Communications (GSM)

890MHz to 960MHz

The same handsets can be used in all countries that use GSM multiplexing.

This is the standard used in Europe, the Far East, Israel, New Zealand,
and Australia. In the United States, GSM is used by VoiceStream.

Personal Communications Service (PCS)

1.8GHz to 1.9GHz

Has the same features as digital cellular. Uses more closely spaced,
smaller antennas than cellular.

Digital cellular services are being implemented differently in the United States
than in Europe. In 1987, the European Union chose a standard called Global System
for Mobile Communications (GSM) for delivering new digital wireless telephony.
In the United States, the Telecommunications Industry Association (TIA) settled
on a similar standard using time-division multiple access. However, shortly
thereafter, many of the Bell telephone companies decided to use a newer method
of multiplexing, code-division multiple access (CDMA). CDMA has greater capacity
than time-division multiple access. The previous table provides a comparison
of the various wireless services available.

Types of Digital Wireless Service

There are two main types of digital wireless service in the United States.
One is called the Personal Communications Service (PCS), and the other is known
as Digital Advanced Mobile Phone Service (D-AMPS). They use different frequencies
or portions of the airwaves to transmit signals.

Both work with either code-division or time-division multiple access.

Both provide the same telephone features.

Both are more difficult to eavesdrop on because the multiplexing scrambles
the voice signals.

PCS towers are smaller and must be spaced closer together. PCS vendors
call their towers antennas because of their small size.

Thus, the United States started down the road with two different standards,
both different than Europe's standards. In addition, the Nextel service works
on a different frequency than that of PCS or D-AMPS (Please spell our Digital
Advanced Mobile Phone Service). Interestingly, there were seven different, incompatible
analog types of cellular service in Europe before digital GSM was installed.
Incompatibility is a problem because customers with digital telephones cannot
use their telephones when they travel to places with incompatible cellular service.

The major challenge for digital cellular is that no one carrier has a complete
nationwide network. PCS providers such as AT&T Wireless and Sprint PCS are
still building out their networks, as is Verizon Wireless. Regional Bell Operating
Companies such as SBC and BellSouth are merging to create networks throughout
the country. Most importantly, there are pockets everywhere, particularly outside
metropolitan areas, with poor service and holes in coverage.